1. Field of the Invention
The present invention relates to a marine reduction and reverse gear unit, and particularly to a marine reduction and reverse gear unit suitable for wakeboats.
2. Description of the Related Art
“V-drive” reduction and reverse gear units, which have an output shaft disposed at an acute angle with respect to an input shaft from an engine, are known (for example, Japanese Unexamined Patent Publication No. 2006-117160, Japanese Examined Patent Publication No. 1994-65904, Japanese Utility Model Publication No. 1994-40560, and U.S. Pat. No. 4,383,829). “Angle-drive” reduction and reverse gear units, which have an output shaft disposed at an obtuse angle with respect to an input shaft, are also known (for example, FIG. 4 of Japanese Examined Patent Publication No. 1994-65904, and U.S. Pat. No. 6,443,286).
In V-drive reduction and reverse gear units, the engine is mounted approximately horizontally on the aft side of the reduction and reverse gear unit. By disposing the entire drive system in one place toward the stern to save space, inboard space can be increased. In angle-drive reduction and reverse gear units, the engine is disposed slightly toward the center from the stern, but is mounted horizontally near the bottom of the boat, whereby inboard space can be increased. Therefore, both types of reduction and reverse gear units are widely used for middle and small marine vessels, such as pleasure boats.
Pleasure boats provided with such reduction and reverse gear units include motorboats called “wakeboats” designed especially for wakeboarding.
Wakeboats usually have a speed range of 0 to 45 mph (miles per hour). When used for wakeboarding, wakeboats run at about 20 mph with added ballast water, while intentionally creating a wake.
To achieve a boat speed of 20 mph, even an engine with a maximum speed of 5000 rpm rotates at about 2200 rpm. The number of gasoline engine revolutions to produce maximum torque is usually at least 3600 rpm, and an engine rotating at about 2200 rpm is likely to produce insufficient torque.